(Meth)acrylic acid is generally prepared by gas phase oxidation of propane, propylene, (meth)acrolein, and the like in the presence of a catalyst. For example, propane, propylene, and the like are converted to (meth)acrylic acid through (meth)acrolein by gas phase oxidation in the presence of an appropriate catalyst in a reactor, and a reaction product mixed gas including (meth)acrylic acid, non-reacted propane or propylene, (meth)acrolein, an inert gas, carbon dioxide, water vapor, and various organic by-products (acetic acid, heavies, and the like) is obtained in the back end of the reactor.
The (meth)acrylic acid-containing mixed gas contacts an absorption solvent including water in a (meth)acrylic acid absorption tower, and is recovered as a (meth)acrylic acid aqueous solution. Further, (meth)acrylic acid-stripped insoluble gas is recycled for a synthesis reaction of (meth)acrylic acid, and a part thereof is incinerated, converted into harmless gas, and discharged. The (meth)acrylic acid aqueous solution is extracted, distilled, and purified to obtain (meth)acrylic acid.
To improve the recovery efficiency of (meth)acrylic aid, various methods of controlling process conditions or a process sequence and the like are being suggested. Among them, as a method for separating water and acetic acid from the (meth)acrylic acid aqueous solution obtained in the (meth)acrylic acid absorption tower, azeotropic distillation using a hydrophobic solvent in a distillation column (300) as shown in FIG. 1 is known. Further, a method of supplying a (meth)acrylic acid aqueous solution to an extraction column to obtain a (meth)acrylic acid extract solution with reduced water content and a raffinate solution thereof, and distilling the extract solution to obtain (meth)acrylic acid, is known.
However, according to the known methods, there are problems in that loss of (meth)acrylic acid in the distillation process is high, and a temperature profile inside the distillation column appears unstable, thus rendering stable operation of the distillation process difficult.